This invention relates to a process for the treatment of fish meat to produce a raw material suitable for the manufacture of powdered fish meat retaining fresh meat activity.
The term "fresh meat activity" as used herein has reference to an undenatured product. Undenatured powdered fish meat has the ability to recover or assume a jelly strength approximating that of a ground paste of fresh fish meat, upon being mixed and kneaded intimately with suitable amounts of water (generally 4 to 5 times the volume of fish meat) and common salt (generally about 3% sodium chloride based on the total weight of powdered fish meat and water).
The present inventor has invented several processes for manufacturing powdered fish meat retaining fresh meat activity (U.S. Application Ser. No. 246,972, filed Apr. 24, 1972, now abandoned in favor of U.S. Ser. No. 555,631, filed March 5, 1975). In these prior processes, however, the majority, as much as 80%, of the sarcoplasmic protein (water-soluble protein generally accounting for 20 to 28% of the whole proteins of fish meat) is inevitably washed away and lost when the fish meat sol raw material is subjected to various conditioning treatments, particularly bleaching, for the production of fish meat powder. With such processes, therefore, it is difficult to improve the yield of product with respect to the fish meat raw material.
In fishes belonging to the Vertebrata, the fish meat protein fundamentally consists of:
1. Water-soluble proteins globular proteins such as myoalbumin, myogen, globulin, etc. (otherwise called sarcoplasmic protein), PA0 2. Salt-soluble proteins fibrous proteins such as actomyosin, tropomyosin, actinine, etc. (otherwise called structural protein), and PA0 3. Stroma proteins (collagen and elastin consisting of connective tissues, ducts and cellular membranes of muscles).
Generally, in the bleaching step employed in preparation of raw ground fish meat paste, the greater part of the aforementioned water-soluble proteins are washed away and lost. In the straining step which follows the steps of bleaching and centrifugal dehydration, the greater part of the aforementioned stroma proteins (sinewy portion of meat, generally called second-order meat) is separated and removed. In preparing the raw ground fish meat paste, usually intended for use in the manufacture of fish paste products, therefore, it has been customary that only the muscle fibrous proteins, accounting for 63 to 76% of the whole proteins of the raw fish meat material, are recovered in the concentrated paste product. Additionally, the waste water which issues from the conventional processes for the preparation of raw ground fish meat paste contains large amounts of the above-described water-soluble proteins and, therefore, represents a potential or actual environmental pollution problem.
In preparing ground fish meat pastes for frozen storage, the prior art method, described above, may avoid, to an extent, the possibility of the protein being denatured in storage. Nevertheless, in the manufacture of powdered fish meat to which the present invention is directed, it is highly desirable, from the viewpoint of improving the product yield and preventing environmental pollution, that loss of water-soluble proteins in waste water should be prevented to the fullest possible extent.